Diesel fuel engines have been used widely in a large array of applications such as transport, heavy machinery or power generation and form a significant component of much equipment in agriculture, mining, construction, and freight and passenger transport for many years. It is known that a combustible gas can be added to a diesel fuel engine air intake. The mixture of the combustible gas with the conventional air intake enhances combustion conditions within the cylinder so as to increase efficiency of the diesel fuel combustion process.
Typically in the prior art, a combustible gas source, for example LPG gas (liquid petroleum gas), is connected to an air inlet of a diesel fuel engine and injected by means of a solenoid valve, at some predetermined rate. This is drawn into the engine air intake stream and mixed in a venturi. The suction of the venturi is provided by the manifold vacuum or pressure difference.
Unfortunately, simple factors in engine performance deterioration significantly reduce the efficiency of the combustible gas injection and hence engine combustion. As a result, the level of the combustible gas injected is not decreased proportionally and this disadvantageously starts to decrease in any delivered efficiency gains and, depending on the deterioration of engine components such as the air filter, can cause the engine to operate inefficiently by providing conditions in which the engine efficiency is lower with a combustible gas injection than without.
Others have recognised these problems and attempted to address them. In one solution, there is provided a method and system of injecting a low concentration of combustible gas into the air intake of a diesel fuel engine. This advantageously significantly increases the combustion efficiency of diesel fuel thereby providing an increase in engine power. This also significantly reduces emissions, especially particulate matter.
With such a significant improvement in combustion efficiency, use of this system has the limitation, especially in naturally aspirated diesel engines, that the engine cannot draw in sufficient air to efficiently combust an increase in diesel fuel. This limitation is the result of engine manufacture and design which is configured to combust the diesel fuel relatively inefficiently compared with an engine operating the abovementioned method and system. In the case of turbo charged engines, it is understood that turbo boost pressure, and hence air in-take volumes, can only be increased so far without risking damage to the turbo charger. In other words, use of this system and method can cause the diesel engine to run out of or draw insufficient air to burn additional fuel so that the full benefits of the system are provided.